The Gemara on today’s daf segues to a discussion about kilayim – forbidden mixtures of plants. A Mishna from Massekhet Kilayim (2:5) is brought that teaches that a field where kanabus (hemp) or luf (arum) are growing cannot be planted with other types of fruit or vegetables, since these plants produce a yield only once every three years. Many different explanations are offered for this teaching.
Rashi explains that because of their longevity they are considered important and therefore are biblically forbidden to be planted with grapevines.
The Kesef Mishna explains the Rambam as forbidding these because they are similar to grapevines because they last for three years.
The Ramban suggests that it is because these plants become intertwined with the vines that there is a problem.
According to the Raavan it is because their plants are cultivated, i.e. they are planted with the intention of keeping them.
It appears that the Gemara’s kanabus is the plant that is still called by that name – cannabis sativa. Already in ancient times this delicate, cultivated plant was used to create fibers used in weaving. It was also used to produce oil – usually for industrial purposes rather than for eating. A specific type of this plant was used to produce hashish, which may have been in use in Talmudic times for medicinal purposes. It is difficult to identify kanabus definitively because of the Gemara’s description that it is a plant that lasts for three years. Some interpret this to mean that its seeds often germinate where the original plant grew so that it appears that the plant remains for many years.
Luf is usually identified as arum palestinium of the aracaae family. This plant has a tuber from which large leaves grow. The plant’s flowers have a unique structure, covered with a special type of leaf called a spathe. The entire flower contains Calcium Oxalate – Ca(COO)2 – which is poisonous and causes a painful rash when touched. For this reason it is not eaten raw by humans, and even most animals cannot eat it. It can, however, be prepared for human consumption by means of cooking or roasting.